It's glyphosate. Not glysophosphate.
Seriously. For years it's 32 ounces per acre in January/February here in the transition zone. Turf, hay fields, whatever. It cleans it up perfectly at that rate.
If I had to bet, you're not getting regeneration of that fescue. Either it's getting dropped in via wind or birds, or its bluegrass or poa popping up in the fall.
You're also wrong to assume that I assume its 1 gallon per 1k sq ft. For myself, it's 1/3 gallon per 1k sq ft and 5 ounces at that rate is pretty close to what I put down out of my Z.
10 ounces per 1 k of glyphosate is ridiculous.